Scheme 1.
Synthesis of polymers 5 and 6.
Fig 1.
OCP vs. time curves for P110 carbon steel corrosion in the absence and presence of different concentrations of (a) 5, (b) 6a and (c) 6b.
Table 1.
Potentiodynamic polarization parameters for P110 carbon steel corrosion in 15% HCl with and without different concentrations of AMCs at 298K.
Fig 2.
Potentiodynamic polarization curves for P110 carbon steel corrosion in the absence and presence of different concentrations of (a) 5, (b) 6a and (c) 6b.
Fig 3.
Nyquist plots for P110 carbon steel corrosion in the absence and presence of different concentrations of (a) 5, (b) 6a and (c) 6b.
Fig 4.
Nyquist plots for P110 carbon steel corrosion in the absence and presence of different concentrations of (a) 5, (b) 6a and (c) 6b.
Table 2.
Electrochemical impedance spectroscope parameters for P110 carbon steel corrosion in 15% HCl with and without different concentrations of AMCs at 298K.
Table 3.
The fitting parameters (intercept, slope and regression coefficient) of different tested isotherm models for the adsorption of AMCs on P110 CS surface in 15% HCl.
Fig 5.
(a) Langmuir, (b) Temkin and (c) Freundlich isotherm plots for the adsorption of AMCs on P110 CS surface in 15% HCl. (d) represent the Arrhenius plots for P110 CS corrosion in 15% HCl with and without AMCs (5, 6a and 6b).
Table 4.
The values of , surface coverage,
and
for the adsorption of AMCs on P110 CS surface in 15% HCl at different temperatures.
Fig 6.
SEM images (at 100x) of (a-1) polished P110 CS and corroded in 15% HCl for 6h (a) in the absence and presence of (b) 5, (c) 6a and (d) 6b.
Fig 7.
EDX spectra of (a-1) polished P110 CS and corroded in 15% HCl for 6h (a) in the absence and presence of (b) 5, (c) 6a and (d) 6b.
Table 5.
DFT parameters derived for 5, 6a and 6b in their solvated phase using B3LYP functional and 6-31G (d,p) basis set.
Fig 8.
Frontier molecular orbitals (FMOs; optimized, HOMO, LUMO) pictures of two neighboring quaternary ammonium-based rings without (5) and with one (6a) or two (6b) alkyl chains and no alkyl chain () used in current DFT study.
Fig 9.
Schematic illustration of physical and chemical adsorption of AMC molecules on P110 CS surface and the formation of corrosion inhibitive film.